class TOML::Keygroup

def navigate_keys(hash, symbolize_keys = false)
  last_index = @nested_keys.length - 1
  @nested_keys.each_with_index do |key, i|
    key = symbolize_keys ? key.to_sym : key
    # do not allow to define more than once just the last key
    if i == last_index && hash.key?(key)
      fail ValueOverwriteError.new(key)
    end
    hash[key] = {} unless hash.key?(key)
    element = hash[key]
    hash = element.is_a?(Array) ? element.last : element
    # check that key has not been defined before as a scalar value
    fail ValueOverwriteError.new(key) unless hash.is_a?(Hash)
  end
  hash
end